1. Field of the Invention
The present invention relates to an angiographic catheter for use in radiography of a lumina of a human such as a heart, a blood vessel of surrounding the heart, a liver, a pancreas, a bile duct and the like.
2. Description of the Related Art
In general, a Judkins type catheter or an Anplatz type catheter has been employed to form an image of a coronary artery, whereas a pigtail type catheter has been employed to form a X-ray image of a left ventricle.
For example, the pigtail type catheter is introduced into a blood vessel near the left ventricle from a femoral artery using a Seldinger method or a sheath method. A guide wire is inserted into the catheter so that the catheter is able to proceed, retreat, rotate or perform other motions. The catheter thereby selects a desired path from a plurality of branching blood vessels and reaches an ascending artery. Thereafter, a distal end portion of the catheter that is curved like a loop is inserted into the left ventricle. In this state, a contrast medium is fed from a proximal end portion of the catheter and injected into the left ventricle in order to form an image thereof.
FIG. 4 is a perspective view illustrating the construction of the generally employed pigtail type catheter, and FIG. 5 is a perspective view illustrating a state where the contrast medium is injected from the catheter as illustrated in FIG. 4.
As illustrated in these figures, the generally employed pigtail type catheter 11 has a distal end opening 13 and a plurality of side apertures 14. The side apertures 14 are located toward the proximal end portion of the catheter 11 from a loop-like deformed portion 12. Hence, a contrast medium 8 is injected from the distal end opening 13 and the respective side apertures 14.
In this case, the respective side apertures 14 are formed perpendicularly to an outer peripheral wall of the catheter 11. However, the contrast medium 8, which is fed under a high pressure, is not injected perpendicularly to the outer peripheral wall of the catheter 11 but obliquely toward the distal end of the catheter 11 (See arrows as illustrated in FIG. 5). This is because the side apertures 14 have a relatively large diameter (0.9 mm).
Hence, a reaction force generated by injection of the contrast medium 8 moves (or displaces) the distal end portion of the catheter 11 toward the proximal end portion of the catheter 11, that is, toward a sinus of Valsalva. Also, the reaction force generated by injection of the contrast medium 8 from the distal end opening 13 of the catheter 11 moves the distal end portion of the catheter 11 laterally, that is, in a direction in which the loop-like deformed portion 12 extends. Consequently, the catheter 11 moves diagonally upward from a location indicated by a dashed line of FIG. 5 (to a location indicated by a solid line).
In the case where injection of the X-ray contrast medium causes such a movement of the catheter, the distal end portion of the catheter tends to be detached from a desired part (left ventricle), and it is impossible to feed the contrast medium into the desired part appropriately and uniformly. As a result, the function of X-ray image formation becomes insufficient.
Although some of the generally employed angiographic catheters are provided with a plurality of side apertures, the number of the side apertures formed in an arbitrary portion of the catheter with an axial length of 10 mm is at most 6. Because the side apertures are arranged at long intervals, the contrast medium injected from the respective side apertures cannot flow into a space corresponding to the desired part uniformly. In order to enhance the function of image formation sufficiently, it is inevitable to increase a flow rate of the contrast medium. In this case, the contrast medium flowing out of the respective side apertures intensely stimulates the lumina of a human.